Modeling and characterization of microelectromechanical systems condenser microphone
MEMS Condenser microphones are becoming a promising technology to substitute the current standard microphones as they have several benefits such as batch fabrication, integration feasibility, low noise level, stable frequency response and high sensitivity; so their demand is increasing and is therefore studied by many researchers. This thesis presents a deep analysis of capacitive MEMS microphones. It presents the results of characterization and modeling of the microphone fabricated using CMOS-MEMS technology. Two different microphones were investigated; firstly, the Sandia Ultraplanar, Multi-level MEMS Technology 5 (SUMMiT V) Condenser microphone was characterized for its membrane displacement with increasing bias voltages. The purpose of this experiment was to investigate the deflection of the membrane and to determine its maximum voltage operating range. C-V measurements were carried out on the samples which gave information about the capacitance, change in capacitance of the structure, gap distance and doping type of the substrate. The second part of the thesis discusses the process flow proposed for fabricating the new microphone designed and developed using surface micromachining technology and compatible with the CMOS technology at the Semiconductor fabrication facility. The membrane performance simulations of the new microphone such as its compliance and natural frequencies have been successfully carried out using CoventorWare, a MEMS simulation package.